Automatic control for electro-plating service



March 6, 1945.

T. R. FBEITAG ET AL.

AUTOMATIC CONTROL FOR ELECTROPLATI'NG SERVICE Filed Sept. 25, 1942 2Sheets-Sheet l 40 FIG.3.

INVENFR;

BY M {M ATTORNEY March 1945- T. R. FREITAG ET AL 2,370,6

AUTOMATIC CONTROL FOR ELECTROPLATING SERVICE I Filed Sept. 25, 1942 2Sheets-Sheet 2 Patented Mar. 6, 1945 AUTOMATIC CONTROL FOR ELECTRO-PLATIN G SERVICE Theodore R. Freitag, Woodbridge Township, MiddlesexCounty, N. J and Edward F. Freitag,

New York, N. Y.

Application September 25, 1942, Serial No. 459,658

Claims. (01. 177-311)" This invention relates to electroplating controlsand is concerned more particularly with a control unit capable ofautomatically controlling the low voltage (0 to 12 v.) high amperageservice (0 to 10,000 amp.) employed in electroplating and in otherenvironments, and wherein a definite time control of the current flow isessential.

In the art of electroplating, it is well known that an article to beplated may have a. metal coating deposited thereon the thickness ofwhich will be a variable unless great care is taken to insure that, withdue regard to the density or pressure of the current passing through theelectrolyte bath and the temperature and specific gravity of the bath,the plating time period is carefully controlled.

The present invention has for a primary aim to render available acontrol unit adapted automatically to control the thickness or theamount of electrodeposition of the metal coating to be applied to theend that articles to be plated may be given uniform coatings of a'specified thickness.

A further aim of the invention is to provide a time control for directcurrent service, having in combination visual and audible signallingmeans so arranged as to give indications before, during, and at thecompletion of an operating cycle of the apparatus to which the controlis adapted so that the operator is certain to be notified of thereliability of the service before'the operating cycl is started, andmoveover, is given continuous notification of the functioning of theapparatus during the selected period for its operation, and again at thecompletion of the operating cycle. In electroplating environments, sucha control relieves the attendant of the necessity of careful manualsupervision, which at times may be impossible of attainment especiallyif one operator has several plating tanks in operation or has otherduties to perform meanwhile.

Heretofore it has been customary to rely upon time clocks, stop watches,and the like, to indicate the correct time at which to open the mainheavy duty switch of a given plating tank, but as such devices dependupon the alertness and promptness of the operator, there frequentlyoccurs unnecessary or over plating of workpieces, and in a relativelyshort period of time they prove to be quite uneconomlcal to use.

The time element in electroplating is highly important not only toinsure that articles to be plated will have deposited thereon a coatingof at least a specified thickness for a specific use or purpose, butthat the coating so applied will not be appreciably thicker thannecessary. From an economic standpoint the excess thickness wastefullydepreciates the electrolyte bath and the metallic electrodes therein(silver, copper, etc.), and in many instances as, for example, indiumplating, a fraction of a minute longer-than-necessary plating intervalmeans a substantial increase in the coating. If the tank operator isbusy at another tank or inadvertently neglects to check the timeaccurately it is a simple matter for the plated coat to build up to anexcess thickness in a very short time.

With the aid of the present invention, however, an operator maysuccessively set in operation one or a battery of electroplating tanksand be assured that each tank will have its plating circuit opened atthe end of a predetermined and preset time interval, and audible andvisual notification given of the completion of the plating operation inrespect to each tank.

Still a further aim of the invention is to render available anautomatically controlled timing device for a heavy duty switch orswitches having the capacity to carry 0 to 10,000 amperes or over insingle or multi-pole, so as definitely to control electroplatingdeposits to a definite and strictly uniform thickness or amount therebyto eliminate need for close manual attention and to expedite and promoteefliciency in electroplating operations of miscellaneous kinds.

In realizing the objectives of this invention it is proposed to embodyan electromagnetic heavy duty switch in the circuit to a. given platingtank and to control the operation thereof through the medium of amanually and automatically operated timing device. In the presentembodiment, the timing device comprises an alternating currentsynchronous motor connected to operate an A..C. relay mechanism which inturn controls the operation of the main switch and portions of thesignalling circuits controlled thereby. Other forms of interval timersmay, of course, be used. An A. C. interval timer is, however, preferredowing to its reliability and accuracy in time measurement and the lackof need for manual attention. The signalling circuits include a red anda green signal lamp, a buzzer, and cut-out switch. Thus, in the presentembodiment of the invention, both direct and alternating currents areinterrelated to provide a compactly arranged, accurate time control fora heavy duty switch and which function first to give an audible andvisual signal at the start of the operating cycle, a different visualsignal during the progress thereof, and again an audible and visualsignal of the completion of the predetermined and preset period ofoperation for which the timer was set.

Other objects and advantages will be in part indicated in the followingdescription and in part rendered apparent therefrom in connection withFigure 1 is a front view of a time control unit embodying thisinvention.

Fig. 2 is a front view of the time controlled heavy duty switch.

Fig. 3 is a side view of the switch illustrated in Fig. 2.

Fig. 4 is a line diagram of the control circuits 'in which the variouselements are shown diagrammatically.

With'reference to Figures 1 and 4, the apparatus therein illustratedcomprises a generator G which furnishes direct current to theelectroplating tank Ta through and under control of a resistance panel Band timer panel T0.

In all electroplating operations the various factors incident tosecuring perfection in the deposited coating are, with the exception ofthe time element, fixed or reasonably ascertainable beforehand. Thecurrent density is controlled by rheostats r and indicated on avoltmeter V and ammeter A, the specific gravity and temperature of thebath by hydrometers and thermometers, and having assured oneself thatthe article W to be plated is thoroughly clean it is then necessary onlyto immerse it in the bath and connect it to the negative or cathode sideof the generator and effect closing of the line switch.

, From that point forward, the article will receive a deposit of metalon its surface that will continue to increase in thickness until thecurrent to the tank is again interrupted.

1 which comprises essentially a heavy copper tank feed bar D', and anequally heavy generator feed bus D", and a heavy pivotallymounted switchlever 38. The feed b'ars D, and D" are securely mounted upon insulationblocks 40 and 4|, and form a unitary assembly capable of convenientmounting within the panel box TC in such manner that the bus bar endsproject through the top thereof.

The generator bus bar D" carries an angular plate 42 at its lower end,which extends forward from the base 4| and overlays the insulated tailend 43 of the switch lever 38, and a flexible connection I2 establishesa permanent connection between the stationary bus bar D-42 and themovable switch lever 38.

The tank feed bus bar D is somewhat J -shaped and mounted to the base 4|so thatthe upturned end thereof underlies the switch'lever 38 and formsa large contact area 39. Between the contact 39 and the pivot of therocking, lever 38, an electromagnet 45 is located and adapted whenenergized to actuate the switch armature 43 clockwise (in Fig. 3)thereby closing the circuit across bus bars D' and D" through members 38and 39.

To insure that a firm electrical contact is made each time the switch isclosed, the contact arm 38 of the switch is arranged to have a slightamount of movement relative to the armature 45 but is held, and movesnormally as a unit therewith, by the action of a spring 41.

To the opposite side of the pivot of the switch lever, an auxiliaryswitch 32 is mounted and so arranged that the resilient contact finger32 maintains contact with its cooperating terminal plate 32 through themajor portion of the movement of the main switch lever 38. Theconstructi-on is such that current will flow through 32 and 32 wheneverthe main contacts 38, 39 are open, and continues to flow therethroughuntil just immediately before members 38, 39 make contact. The switch32, in accordance with this invention, controls a holding circuit for arelay DCR (Fig. 4) which in turn controls a portion of the circuit tothe coil 45 of the main switch. Hence it is important to continue thecircuit to the direct current relay efiective until after the heavyswitch armature and parts carried thereby are in motion and about toclose on contact 39. When the auxiliary switch 32 opens, the startingcircuit for the controlling relay is broken 88 firmly in engagement withthe tank feed bar D.

The elements making up the time control for the heavy duty switch HD,including control relays, switches, signals, and timer, are of standard,well known, construction and in the interests of clarity are illustratedsymbolically in Fig. 4, to which reference will now be made.

Having connected 9. clean article W to the cathode side of the platingtank, the operator d0 closes a double pole manual switch S at the frontof the panel TC. One pair of contacts 30 of the switch S is wired foralternating current A. C. and controls the synchronous motor T, throughlines 49, 58, switch 31,1ine 5l, motor T, and line 52, and the other.pair of contacts 3| iswired for direct current service, through elementsD4, 32, I, 3|, 2, GT, Re, I3, C, and I5. The closing of switch 3Icompletes a portion of the circuit across the D. C. bus bars D and C,through line l2, a normally closed contact 32 of the heavy duty switchHD, lines I and 2, green light Gr, line I3, and parallel connected bellB, (through 2, 33, and I6). Thus the closing of the switch S completes aportion of the circuit to the time device T, the green lamp Gr lights,and the bell B rings. As the current for the signals is directed throughelements ofthe heavy duty switch, the initial ringing and lightingthereof serves to give an advance check on the readiness of the :devicesto function at the critical time, namely, at the completion of theplating cycle, and also to give notice that current is at the mainswitch ready to flow through the tank circuit.

To stop the ringing of the bell, the operator presses the push button Pwhich (through lines 2, 3, and 4) energizes the coil of a direct currentrelay DCR. in the circuit controlled. by the manual switch 3!. Theenergizing of the D. C. relay operates to close two switches 34, 35 andto open the bell switch 33. The closing of switch 35 establishes aholding circuit around the push button P, through line 5 and resistor R"coil DCR and line 4 so that the coil DCR continues effective to hold thebell switch 33 open.

The closing of switch 34 completes a portion of the circuit to the coil45 of the electromagnetic heavy duty switch HD in the circuit comprisinglines 6, I, 8, switch 34, lines 3, I0, switch 36, and line II. Thiscontrol circuit embodies an alternating current relay ACR, the switch 36thereof being normally open, and which is closed' only when .theoperator sets the control handle E of the timer to the time perioddesired. Operation of the handle E to the correct time indication,automatically closes a switch 31 connected in series with the manualswitch 38, and this will start the timer T operating, and effectenergization of the alternating current relay ACR, through A. C. lines43, 50, 53, 54, and 52. The alternating current relay, ACR operatesswitch 38 to complete the circuit across lines 8 age, high amperage,make or break switch automatically controlled by an interval timerparticularly suitable for controlling, by predetermination, thethickness of metal coatings to be applied by regular electroplatingequipment. The entire control being compactly arranged and built intoaportable cabinet that lends itself readily adaptable for quickinstallation in any given tank circuit. With a control unit of thischaracter it is and II to the coil of the heavy duty line switch HD, Theswitch arm 38 immediately moves in a. direction away from contact 32(line I) and closes on contact 39 which is in effect a copper bus bar Dconnected with the cathode side of the plating tank. With theparts intheir effective positions, direct current from the generator flows tothe anode of the tank, through the electrolyte to the cathode, throughresistance panel R, bus bar D, contacts 39, 38 of main switch HD, lineI2, negative bus bar D" back to the generator. A connection I5 is alsotaken off the positive'side oi the generator and leads to the terminalblock C in the control panel TC.

Across the tank bus D. and the positive bus C, a red lamp Re isconnected (lines I3, I4) which lights up as soon as the current isflowing through themain switch HD.

The closing of the main switch arm 38 simultaneously breaks theconnection at 32 across lines I and I2, inthe circuit I2, I, 3|, 2, G1,I3, C. and the green light Gr goes out, the holding circuit (2, 35, R",DCR, 4) across switch 35 through resistor coil R" to the coil of relayDCR, is broken and relay switches 34; 35 open and the bell switch 33closes. The bell B does not ring, however, be-' cause its circuit I2, Iis open at 32.

Meanwhile, direct current to the coil of the heavy duty switch HD ispassing through lines 6, 'I resistor R, line 8, Ill, A. C. relay switch38, and line I I in suflicient strength to hold the main switch arm 38closed on contact 38.

When the timer T has operated the predetermined period of time, which isadjustable by moving the pointer E to the selected time indicatedmarking, the switch 31 therein opens and breaks the circuit to thealternating current relay IACR and the switch 38 thereof opens, directcurrent to the coil of the heavy duty switch HD is interrupted and themain switch arm 38 opens the tank circuit and the red light circuit atthe contact 39. As the main switch opens, auxiliary switch 32 thereofcloses, circuits I2; I, 2,.Gr, I3, and I2, I, 2, 33, B, and I8 arecompleted, the green light Gr lights up, and the bell B gives audiblenotice of the completion of the plating period. The operator-is thuscalled to the plating tank and proceeds to remove the completed work,and stops the ringing of the alarm by pressing the push button P, which,through lines 2, 3, DCR and 4, opens the switch 33. The control circuitsare now preconditioned to repeat the plating cycle upon the moving ofthe pointer E to the desired time setting.

Should there be no need to repeat, the manual switch S is opened andboth A. C. and D. C. controls are rendered ineffective.

From the foregoing it will be perceived that the present inventionrenders available a low voltno longer necessary to employ complicatedand delicate measuring instruments calibrated for use on only one'kindof metal for a given weight or thickness of deposit, as the presentunit, by its exercise of definite control of the time factor, is

capable of use in controlling the thickness of any metal deposited andis, therefore, usable with any plating tank. Continuously uniformdeposits of a iven thickness on an unlimited number .of pieces may beachieved with this type of control merely by repeatedly setting theinterval timer to the same number of minutes or hour specified by theworking chart. Losses in production time or in the electrolyte and anodematerials have likewise been eliminated by virtue of the automaticcircuit breaking features and built-in signalling instrumentalities ofthe unit, and there ,is no worry to the pl-ater as to whether a tankload is being under or over plated.

Withoutfurther analysis, the foregoing will so fully reveal the gist ofthis invention that others can, by applyingcurrent knowledge, readilyadapt it for various utilizations by retaining one or more of thefeatures that, from the standpoint of the prior art, fairly constituteessential characteristics of either the generic or specific aspects ofthis invention and, therefore, such adaptations should be, and areintended to be, comprehended within the meaning and range of equivalencyof the following claims.

Having thus revealed this invention, we claim as new and desire tosecure the following combinations and elements, or equivalents thereof,by Letters Patent of the United States:

1. Timing apparatus for direct current service comprising a normallyopen line switch; a direct current operated solenoid adapted whenenergized to effect closing of said line switch; a control system forthe said solenoid embodying therein a direct current operated relayswitch and an alternating current operated relay switch connected inseries with said solenoid; a source of atlernating current and a circuitfrom aid source for operating said alternating current relay; asynchronous timed switch in said circuit and energized from said source;interconnected man= ually operated switches in series with the operatingcircuit of said direct current relay and said alternating currentcircuit respectively and simultaneously operable to close the circuit ofthe direct current relay and close said alternating current circuit atone point, said timed switch being responsive to the setting thereof fora selected time period to close the circuit to said alternating currentrelay at another point, maintain it closed for such time period and thento open said circuit whereby when said interconnected switches areclosed and said direct current relay is energized the setting of saidtimed switch effects closure of said line switch for said selected timeperiod.

2. Timing apparatus for direct current service comprising a normallyopen line switch; a direct current operated solenoid adapted whenenergized to effect closing of said line switch; a control system forthe said solenoid embodying qtherein a direct current operated startingrelay switch and an alternating current operated relay switch connectedin series with said solenoid; a

source of alternating current and a circuit from said source foroperating said alternating current relay; a synchronous timed switch insaid circuit and energized from said source; interc'oncuit of the direct.current relay for operation and close said alternating current circuitat one point; additional switch means in the circuit of said directcurrent relay adapted when actuated to closed position to energize saiddirect current relay; said timed switch being responsive to the settingthereof for a selected time period to close the circuit to saidalternating current relay at 'a remaining point, maintain it closed forsuch time period and then to open said circuit whereby when saidinterconnected switches are closed and said direct current relay isenergized the setting of said timed switch effects closure of said lineswitch for said selected time period,

3. The combination set forth in claim 1 including direct'currentoperated signal means connected to said line switch for imparting asignal when the said switch is in open position and another signal whenthe said switch is in closed position. E

4. The combination set forth in claim 2 including the provision ofsignal means rendered efiective-on the closure of said interconnectedswitches and rendered ineffective when said alternating current relay isenergized.

5. The combination set forth in claim 2 including the provision ofsignal means connected with said direct current operated relay. switchwhen the latter is inopen position and rendered ineffective when saidrelay is energized, additional signal means connected to said lineswitch effective when said switch is in open position, and

another signal means connected with said line switch and efiective whensaid switch is in closed position.

- THEODORE R. FREITAG.

EDWARD F. FREITAG.

